Mohs micrographic surgery and dermatopathology concordance: An analysis of 1421 Mohs cases over 17 years

The success of Mohs micrographic surgery depends on the surgeon’s ability to correctly interpret intraoperative frozen sections. This retrospective study analyzed the rate of concordance between Mohs surgeons and dermatopathologists in reading slides from Mohs surgery cases. A dermatopathologist reviewed all the frozen sections and the corresponding Mohs map for every 30th Mohs case at a practice employing 6 different Mohs surgeons during 2001-2017. Cases in which the dermatopathologist and the Mohs surgeon disagreed on the interpretation were noted. The concordance rate between Mohs surgeons and dermatopathologists was 99.79%. The 3 discordant cases included a case of squamous cell carcinoma, a case of superficial basal cell carcinoma, and a case of hypertrophic squamous cell carcinoma in situ. This analysis is limited to fellowship-trained Mohs surgeons and, therefore, might not be applicable to all physicians who perform Mohs. Fellowship-trained Mohs surgeons show high concordance with board-certified dermatopathologists in the accurate and precise interpretation of histology slides in the setting of Mohs micrographic surgery.